Field
The present disclosure relates generally to communication systems, and more particularly, to performing a channel state information (CSI) measurement in an enhanced machine-type communication (eMTC) or a narrowband (NB) internet-of-things (NB-IoT) communication.
Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In wireless communications, CSI may refer to known channel properties of a communication link between a user equipment (UE) and an evolved Node B (eNB). CSI may indicate how a signal (e.g., transmission) propagates from the eNB to the UE, and may represent the combined effect of, for example, scattering, fading, and power decay with distance. A UE not communicating via eMTC or NB-IoT may be able to measure CSI using a single subframe in a transmission from the eNB. A CSI measurement may be reported back to the eNB, and the eNB may use the CSI report to adapt transmissions to current channel conditions, which may help achieve reliable communication with high data rates in multiple access networks
Due to the low signal-to-noise ratio (SNR) associated with eMTC and/or NB-IoT, a UE may not be able to perform a CSI measurement using a single subframe. Thus, there is an unmet need for performing CSI measurements in eMTC and/or NB-IoT regardless of a low SNR.